The present invention relates to a stator of an electrical motor, and more particularly to improvements in the stator construction in an electrical motor composed of a rotor and a stator, which has a plurality of pole pieces arranged in radial shape on the outer periphery of the rotor and has windings of coils disposed on these pole pieces.
Conventionally, FIG. 13 shows one example of a stator having been employed in this type of electrical motor, in which a plurality of radial poles 1 project inwardly from the inner face of the casing of a yoke member 4. the Windings of coils 3 are provided on each pole 1 a layer of insulating material separates the windings 3 from the poles 1.
FIG. 14 shows another embodiment, wherein each pole 1 is separate from the casing of yoke member 4. The windings of coil 3 are provided on the layers of insulating material 2 on the individual poles 2. A convex portion la of the pole member 1 is fixedly inserted into the concave portion 4a of the yoke member 4.
In manufacture of the motor illustrated in FIG. 13, the winding operation has to be performed by the use of the clearance 5 among the respective poles 1, and the narrow space 5 on the inner face of the yoke member 4. Hence, the winding operation becomes difficult particularly with small-sized motors, thus resulting in extremely inferior operational property.
However, the construction shown in FIG. 14 is free from this problem, the winding operation may be performed on the poles prior to insertion in the yoke member 4 so that the operation is extremely easy to perform. In small-sized motors, however, the mounting operation on the yoke member 4 is difficult to perform because the pole piece 1 itself is small, thus resulting in extremely inferior operational property. Accordingly, the construction of FIG. 14 is not particularly suitable for the manufacture of small-sized motors.